Professor: Sana Odeh Functions. Math Functions (generating random functions) Reading:

Transcription

1 1 Professor: Sana Odeh Functions Math Functions (generating random functions) Reading:

2 2 Functions Two types of Functions: Built-in functions: (efficient functions that are already written to use in your program) Such as input(), print() Now, you can also use math modules which provides many useful functions such as math.sqrt(9) 3 math.pow(2,4) 16 You need to import math module at the beginning of your program A module can have many functions that you extend and use in your program User defined functions: Programmer can write their own functions such as a function to compute average, another function to fin maximum and another to find minimum number. Will discuss this in future classes

3 3 Functions Now, you can also use math modules which provides many useful functions # using math modules' functions import math numsqrt = math.sqrt(9) print ("sqrt of ", 9, " is ", numsqrt) numpow= math.pow(2,4) print ("num ", 2, " to the power of ", 4, " is ", numpow)

4 More built-in Functions to use with strings Two types of Functions: Built-in functions to use with strings: len(stringname) To get the length of a string: # using len() function which returns the number of characters in a string size = len('obama') print(size) # prints 5 4 size = len('python') print(size) # prints 6 letter ='c' size = len(letter) print(size) size = len('') # prints 1 print(size) # prints 0 because it s an empty string phrase = 'It\'s snowing outside!' size = len(phrase) print(size) # prints 21

5 Random number Functions 5 make sure to import random in the beginning of the program in order to use these random functions 1) Integer Random numbers: random.randint(a,b) produces the following range: # Returns a random integer N such that a <= N <= b. #Example: random.randint(1,6) produces 1 <= N <= 6. This can produce 1 or 6 or 4 or 3 2) Float random numbers: random.random() # produces a float number : 0.0 <= N < 1.0 such as or How can we force random.random() to produce integers?

6 6 random.randint() and random.random() # generating random numbers import random # random.randint(a, b) # Return a random integer N such that a <= N <= b. intrand = random.randint(1, 6) print("you generated an integer random number from 1 to 6 (inclusive): ", intrand) #random.random() generates a float number such as 0 <= number < 1. # example: or random_float = random.random() print("you generated float random number 0 <= number < 1: ",random_float)

7 7 random.choice() and random.random() # Prof Sana odeh / V / New York University # generating random.choice('hello') import random letter = random.choice('abcdefghij') # Choose a random element print(letter) # Choose a random element from alphabet letter2 = random.choice('abcdefghijklmnopqrstuvxyz') print(letter2) charnum = random.choice(' ') # Choose a random number (but its treated as characters) print(charnum) print("type(charnum)", type(charnum))

8 8 # swaps Swaps num1, num2 = 7,10.9 print ("num1 is : ",num1) print ("num2 is : ",num2) # swapping values num1, num2 = num2, num1 print ("num1 and num2 after swap") print ("num1 is : ",num1) print ("num2 is : ",num2) word, num2 = num2, word print ("word and num2 after swap") print ("word is : ",word) print ("num2 is : ",num2) print ("type(word) : ",type(word)) print ("type(num2) : ",type(num2))

9 9 Assignment: Multiple assignments num=5 # num points to value 5 multiple assignments: word, num1, num2 = "one", 2,3.0 # word points to one # num1 points to value 2 # num2 points to value 3.0

10 10 User-Defined functions The following slides are from this source: Copyright 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley

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